Apparatus for shaping metallic pieces by shock waves

ABSTRACT

Metallic pieces are shaped by shock waves created by firing a charge within the piece to be shaped and shortly thereafter by the firing of a charge on top of a cap seated on the piece to be shaped. The cap has a central opening into the piece to be shaped and into a receptacle opening upwardly and located on the cap, the second explosive charge being located within the receptacle.

United States Patent Nicot 51 May 16, 1972 [54] APPARATUS FOR SHAPING METALLIC PIECES BY SHOCK WAVES [72] Inventor:

[73] Assignee: Creusot-Loire, Paris, France [22] Filed: July 23, 1970 [21] App]. No.: 57,733

Gerard Nicot, Pamiers, France 3,559,434 2/1971 Keinanen ..72/56 FOREIGN PATENTS OR APPLICATIONS 158,254 10/1962 U.S.S.R. ..72/56 Primary Examiner-Richard J. Herbst Attorney-Cameron, Kerkam & Sutton [5 7] ABSTRACT Metallic pieces are shaped by shock waves created by firing a charge within the piece to be shaped and shortly thereafter by the firing of a charge on top of a cap seated on the piece to be shaped. The cap has a central opening into the piece to be shaped and into a receptacle opening upwardly and located on the cap, the second explosive charge being located within the receptacle.

8 Claims, 4 Drawing Figures PATENTEBMAY 16 I972 SHEET 1 [IF 2 APPARATUS FOR SHAPING METALLIC PIECES BY SHOCK WAVES BACKGROUND OF THE INVENTION The present invention relates to shaping of metallic pieces by shock waves created by the firing of explosives.

It is now known to use the energy from an explosion transferred by shock waves to shape metallic pieces located in a matrix which gives the piece its final dimensions. Shaping by shock wave can be provided by direct contact of the explosive with the piece or through an intermediate body of suitable nature.

It is also known to deform tubular bodies having thin walls or made up of plurality of thin concentric walls having open cylindrical ends using explosive charges having particular shape in such a way as to equalize the explosive effects with the charges placed in the axis of and distributed along the length of the piece.

The shock waves acting on thepieces may result in a modification of the shape to obtain desired shapes and may also modify mechanical characteristics as well as the physical characteristics of the shaped piece.

The use of shock waves from explosives is primarily em-,

ployed to change the shape of pieces which would be difficult to treat by any other process in view of their dimensions or of the thickness oftheir walls.

Known processes and apparatuses utilizing explosives for changing the shape of pieces are not in general use and are not usually efficient in the case of very thick pieces or pieces of small height as compared to diameter.

SUMMARY OF THE INVENTION The present invention relates to apparatus for the easily shaping of pieces utilizing forces from explosives.

In accordance with the invention, shaping apparatus using shock waves on open ended metallic pieces includes an explosive charge and has a base on which one of the open ends of the piece is placed; a cap is mounted on the other open end of the piece; a receptacle opening upward is located above the cap; at least one explosive charge is located within the piece to be shaped; the cap has an opening communicating with the interior of the piece and the interior of the receptacle; and at least one explosive charge is located above the cap.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention will now be described with reference to the accompanying drawings in which like reference characters indicate like parts. In the accompanying drawings,

FIG. 1 is a cross'sectional view of one embodiment of apparatus in accordance with the present invention through the vertical axis of the piece to be shaped;

FIG. 2 is a view similar to that of FIG. 1 showing the piece to be shaped as a hyperboloid;

FIG. 3 is another embodiment of the present concept which is a modification of that of FIG. 1; and

FIG. 4 shows another embodiment of the present concept in which the piece to be shaped is a truncated cone which becomes cylindrical.

DESCRIPTION OF PREFERRED EMBODIMENTS In the embodiment of FIG. 1 there is a metal base 1 resting on surface 2. The piece to be shaped is a steel hoop 3 which rests on base 1. Above hoop 3 is a metallic cap 4 provided with an opening 5.

A receptacle 6 is placed on cap 4. Receptacle 6 can, in accordance with an embodiment of the present invention, be secured in advance to cap 4.

The receptacle 4 can be of metal which can be welded to cap 4, and may also be of destructable material such as impermeable cardboard.

Within piece 3 are placed explosive charges 7 mounted, for example, on a vertical rod 8 and the fuse for the charges extends along this rod.

In this apparatus, cap 4 would have a tendency to blow off during the explosion of charges 7. To keep cap 4 in place, supplemental charges 9 are placed above cap 4 and are exploded slightly later than charges 7. The difference in time of explosion between charges 9 and charges 7 can be very easily obtained by utilizing a fuse 10 for charges 9 which is longer than the fuse for charges 7.

Additional pieces 11 to be treated may b placed within receptacle 6, for example, to hammer-harden them.

The apparatus just described is used as follows. When the apparatus is assembled as described, the charges are fired. The first charges which fire are the group of charges 7, then charges 9 are fired at a slightly later time and the action of charges 9 maintains cap 4 in position on piece 3. Preferably, before firing, the assembly of piece 3, opening 5 and receptacle 6 is filled with a suitable material, for example, water forming a packing within the apparatus. At the moment of explosion, the water is dissipated passing through opening 5 and is evacuated to the outside.

It is possible in an installation such as that described to treat pieces 3 at extremely variable temperatures in accordance with objects to be obtained. These pieces can be, for example, chilled to 0 centigrade or can be heated at elevated temperatures even to red heat. In'this last case, water cannot be used within the apparatus formed by piece 3, opening 5 and'receptacle 6 and the packing should then be of a granular material such as sand. The interior of the apparatus is then filled with sand; a vertical duct is formed in the sand and the explosive charges introduced into the duct, the charges being protected against heat by means of thermal insulation such as asbestos.

For certain uses, the interior of the apparatus may contain only air and neither liquid nor granular material is used as packing. Air is normally used within the apparatus when the thickness of the pieces to be shaped is relatively small.

FIG. 2 shows a variation of the present concept in which wooden shims 12 and 13 are placed, respectively, between metallic base 1 and piece 14 and between piece 14 and cap 4. The shims l2 and 13 are easily destroyed by the explosion with the result thatthe forces of the explosion are greater in the central zone of piece 14 than the forces produced adjacent shims l2 and 13. A piece 14 shaped as a hyperboloid can therefore be transformed into a cylindrical piece using these shims. Further, the forces acting at the center of the piece can be increased by concentrating the charges there or by adding a supplemental charge in the central zone. It should be understood that the position of the charges can be changed as required for the shaping of the pieces 3 or 14.

FIG. 2 shows another supplemental characteristic of the present invention in which a sealing sheet 16 seals the interior of the apparatus formed by piece 14, base 1, opening 5 and receptacle 6. Sealing of the apparatus in this way is very easily done by introducing within the enclosure a sack, for example, of plastic material, which readily takes the shape of the interior of the apparatus. At the moment of explosion, this sack is expanded toward the extremities and corners of the interior of the apparatus and principally into the spaces provided by shims 12 and 13 and engages the remaining walls of the enclosure.

In FIGS. 1 and 2, the shock waves have a direct action on the interior walls of pieces 3 or 14 and also have an indirect action by reflection of the shock waves on the upper surface of base 1 and on the lower surface of cap 4.

For certain uses, it is desirable to avoid the indirect action of the-shock waves by reflection on these surfaces. In such a situation, a destructible wall 17 is located between shims I2 and 13 and the open extremities of piece 3. Wall 17 may be made of wood. This wall is destroyed at the moment of explosion and the shock waves are not reflected on the upper surface of base 1 or on lower surface of cap 4. Destructible walls 17 are replaced for each firing of the device. It should be un- I by a sack similar to sack 16 of FIG. 2. At the instant of explosion the shock waves act directly and preferentially on the upper intemal wall of piece'l8 and indirectly by reflecting on the face ofbase 1. In view of shims 19 which are destroyed by the explosion, the effect of the shock wave at the base of piece -18 is less than the effect of the shock waves at the upper part thereof. The truncated conical piece is therefore transformed into a cylindrical shape.

In the several embodiments discussed above, cap 4 has an orifice 5. This orifice cooperates with the action of charges 9 to maintain cap 4 in position at the moment of firing. It has been found that the movement of cap 4 is negligible or at least without serious efi'cct when the diameter of orifice is at least equal to half the diameter of the piece 3.

As shown by the embodiments discussed above, the pieces can be shaped without the use of a matrix and may have various shapes. They can be cylinders, truncated cones, hyperboloids or barrel-shaped. They may have prismatic faces; be nonregular thicknesses; and the walls may have lands and grooves thereon.

The desired shapes may be obtained by one or more firings of explosive charges depending upon the difiiculty of shaping or the thickness of the piece. It is quite obvious that a piece having a thickness of 5 mm is more easily worked than a piece having a wall thickness of 200 mm.

The apparatus described above can be utilized for shaping pieces of metal or of alloys, for example, steel and iron alloys, copper alloys and alloys of aluminum or titanium.

ter of said piece.

The present invention is not limited to the embodiments discussed above and various modifications may now be suggested to those skilled in the art without departing from the present inventive concept. I

Reference should therefore be had to the appended claims to determine the scope of this'invention.

lclaim:

1. Matrix free apparatus for shaping open-ended metallic pieces by shock waves from explosive charges comprising a base, said'base being adapted to receive an open-ended work piece mounted on one end on said base, a cap on the other open end of said piece, a receptacle opening upwardly located on said cap, at least one explosive charge within said piece, an opening in said cap opening the interior of said piece to the interior of said receptacle, at least one explosive charge located above said cap and means for delaying the explosion of said charge on said cap with respect to the explosion of said charge in said piece.

2. Apparatus as described in claim 1, said base being metallic.

3. Apparatus as described in claim 1, including shims between said piece and said base and between said piece and said cap.

4. Apparatus as described in claim 1, including asealing member within said piece extending from said base through said cap and through said receptacle.

5. Apparatus as described in claim 1, including destructible panels at least between one end of said piece and said base or between said piece and said cap.

6. Apparatus as described in claim 1, including an additional piece to be treated located in said receptacle.

7. Apparatus as described in claim 1, including a liquid or granular packing in said piece.

8. Apparatus as described in claim 1, the diameter of said opening in said cap being at least equal to one-half the diame- 

1. Matrix free apparatus for shaping open-ended metallic pieces by shock waves from explosive charges comprising a base, said base being adapted to receive an open-ended work piece mounted on one end on said base, a cap on the other open end of said piece, a receptacle opening upwardly located on said cap, at least one explosive charge within said piece, an opening in said cap opening the interior of said piece to the interior of said receptacle, at least one explosive charge located above said cap and means for delaying the explosion of said charge on said cap with respect to the explosion of said charge in said piece.
 2. Apparatus as described in claim 1, said base being metallic.
 3. Apparatus as described in claim 1, including shims between said piece and said base and between said piece and said cap.
 4. Apparatus as described in claim 1, including a sealing member within said piece extending from said base through said cap and through said reCeptacle.
 5. Apparatus as described in claim 1, including destructible panels at least between one end of said piece and said base or between said piece and said cap.
 6. Apparatus as described in claim 1, including an additional piece to be treated located in said receptacle.
 7. Apparatus as described in claim 1, including a liquid or granular packing in said piece.
 8. Apparatus as described in claim 1, the diameter of said opening in said cap being at least equal to one-half the diameter of said piece. 